The present invention relates to the field of fluid mixing valve assemblies. More particularly, the invention concerns an improved thermostatically controlled mixing valve assembly in which a thermostat is immersed in the fluid flowing through the valve.
Thermostatic control valve assemblies are well known in the art and have long been utilized in various applications including group showers, washing stations, hospital hydrotherapy installations and in many industrial applications where precision thermostatic water blending is essential. In order to operate properly, the hot and cold water entering such a valve assembly must be thoroughly blended before the temperature of the mixture is sensed by the thermostat. If the hot and cold water are not adequately mixed, the valve assembly can behave erratically because the temperature sensor sees pockets of hot and cold water instead of a mixture that is at a single temperature throughout. One problem that has long persisted in the art is the inability of most valve assemblies to adequately mix the hot and cold water over a wide range of flow rates. Consequently, multiple valves often have to be used to satisfy flow requirements.
Another problem that has persisted in the art is the physical size of the valve assembly required for a specific application. Often, the valve assembly is simply too large because of the need for a large mixing chamber to adequately mix the hot and cold water. What is needed is a thermostatic control valve assembly having an improved mixing chamber that has the ability to thoroughly mix the hot and cold water over a wide range of flow rates, and which does so in a smaller physical space than valve assemblies currently known in the art.
One such valve assembly featuring an improved mixing chamber is disclosed in U.S. Pat. No. 5,203,496 which is assigned to the assignee of the present invention. It is now desired to improve the operation of such valve assemblies by providing a mixing valve assembly which operates with reduced pressure drop across the valve assembly, while still thoroughly mixing the hot and cold fluids.
A thermostatic control valve assembly for continuously mixing a hot first fluid with a cold second fluid to continuously produce a mixed fluid at a constant temperature according to one embodiment of the present invention comprises a cold fluid inlet, a hot fluid inlet, a mixing dome defining a mixing chamber, a thermostatically controlled flow control valve and an operably connected thermostat for adjusting the flow of the hot and cold fluids into the mixing chamber. The mixing dome includes a plurality of baffles sequentially placed in the flow path to promote better mixing of the hot and cold fluids before the mixed fluid contacts the thermostat disposed in the fluid flow path.
In one aspect of the invention, each baffle projects into the flow stream and is angled from the mixing dome wall in a direction contrary to the direction of flow. The mixing performance is further improved by angularly displacing the each baffle with respect to each other to impart a twisting movement to the fluid. The mixing dome includes means for supporting the thermostat between the baffles and the fluid outlet of the dome.
A general object of the present invention is to provide an improved thermostatic control valve assembly. A specific object is to provide a valve assembly that more efficiently mixes hot and cold fluids for accurately sensing the temperature of the mixture.
A further objective is to provide a valve assembly that provides effectively mixed hot and cold fluids with reduced pressure drop between the valve and valve outlet. Related objects and advantages of the present invention will be apparent from the following description.